  var canvas = document.getElementById("tetris");
  var context = canvas.getContext("2d");
  var padding = 6,
  size = 32,
  minX = 0,
  maxX = 10,
  minY = 0,
  maxY = 18,
  score = 0,
  level = 1,
  marks = 0;
  var gameMap = new Array(); //游戏地图，二维数组
  var gameTimer;
  initGameMap();
  //绘制垂直线条
  drawGrid();
  var arrays = basicBlockType();
  var blockIndex = getRandomIndex();
  //随机画一个方块意思意思
  var block = getPointByCode(blockIndex);
  context.fillStyle = getBlockColorByIndex(blockIndex);
  drawBlock(block);
  /**

  * 初始化游戏地图

  */
  function initGameMap() {
  for (var i = 0; i < maxY; i++) {
   var row = new Array();
   for (var j = 0; j < maxX; j++) {
   row[j] = false;
   }
   gameMap[i] = row;
  }
  }
  /**

  * 方块旋转

  * 顺时针：

  * A.x =O.y + O.x - B.y

  * A.y =O.y - O.x + B.x

  */
  function round() {
  //正方形的方块不响应旋转  
  if (blockIndex == 4) {
   return;
  }
  //循环处理当前的方块，找新的旋转点
  for (var i = 1; i < block.length; i++) {
   var o = block[0];
   var point = block[i];
   //旋转后的位置不能与现有格子的方块冲突
   var tempX = o.y + o.x - point.y;
   var tempY = o.y - o.x + point.x;
   if (isOverZone(tempX, tempY)) {
   return; //不可旋转
   }
  }
  clearBlock();
  //可以旋转，设置新的旋转后的坐标
  for (var i = 1; i < block.length; i++) {
   var o = block[0];
   var point = block[i];
   //旋转后的位置不能与现有格子的方块冲突
   var tempX = o.y + o.x - point.y;
   var tempY = o.y - o.x + point.x;
   block[i] = {
   x: tempX,
   y: tempY
   };
  }
  drawBlock();
  }
  function moveDown() {
  
  var overFlag = canOver();
  if(overFlag){
   //如果不能向下移动了，将当前的方块坐标载入地图
   window.clearInterval(gameTimer);
   add2GameMap();
   //清除游戏区域内的不同颜色的格子，使用单一颜色重新绘制地图堆积物
   redrawGameMap();
   return;//游戏结束
  }
  
  var flag = moveTo(0, 1);
  //如果可以移动，则继续移动
  if (flag) {
   return;
  }
  //如果不能向下移动了，将当前的方块坐标载入地图
  add2GameMap();
  
  //进行消行动作
  clearLines();
  //清除游戏区域内的不同颜色的格子，使用单一颜色重新绘制地图堆积物
  redrawGameMap();
  //如果不能向下移动，则继续下一个方块
  nextBlock();
  }
  
  /**

  * 消行动作，返回消除的行数

  */
 
  function clearLines() {
  var clearRowList = new Array();
  for (var i = 0; i < maxY; i++) {
   var flag = true;
   for (var j = 0; j < maxX; j++) {
   if (gameMap[i][j] == false) {
    flag = false;
    break;
   }
   }
   if (flag) {
   clearRowList.push(i);
    //记录消除行号的索引
    marks++;
    mark.innerHTML = "分数：" + marks ;//分数记录
   }
  }
  var clearRows = clearRowList.length;
  //所谓的消行就是将待消除行的索引，下方所有的格子上移动
  for (var x = 0; x < clearRows; x++) {
   var index = clearRowList[x];
   for (var i = index; i > 0; i--) {
   for (var j = 0; j < maxX; j++) {
    gameMap[i][j] = gameMap[i - 1][j];
   }
   }
  }
  if (clearRows > 0) {
   for (var i = 0; i < maxY; i++) {
   //此处可以限制满足相关条件的方块进行清除操作&& j < clearRowList[clearRows - 1]
   for (var j = 0; j < maxX; j++) {
    if (gameMap[i][j] == false) {
    clearBlockByPoint(i, j);
    
    }
   }
   
   }
  }
  }
  /**

  * 重绘游戏地图

  */
  function redrawGameMap() {
  drawGrid();
  for (var i = 0; i < maxY; i++) {
   for (var j = 0; j < maxX; j++) {
   if (gameMap[i][j]) {
    roadBlock(j, i);
   }
   }
  }
  }
  /**

  * 打印阴影地图

  */
  function drawShadowBlock() {
  var currentBlock = block;
  var shadowPoints = getCanMoveDown();
  if (shadowPoints != null && shadowPoints.length > 0) {
   for (var i = 0; i < shadowPoints.length; i++) {
   var point = shadowPoints[i];
   if (point == null) {
    continue;
   }
   var start = point.x * size;
   var end = point.y * size;
   context.fillStyle = "#abcdef";
   context.fillRect(start, end, size, size);
   context.strokeStyle = "black";
   context.strokeRect(start, end, size, size);
   }
  }
  }
  /**

  * 返回最多可移动到的坐标位置（统计总共可以下落多少步骤）

  * @return最多可移动到的坐标位置

  */
  function getCanMoveDown() {
  var nps = canMove(0, 1, block);
  var last = null;
  if (nps != null) {
   last = new Array();
   while ((nps = canMove(0, 1, nps)) != null) {
   if (nps != null) {
    last = nps;
   }
   }
  }
  return last;
  }
  
  function canOver(){
  var flag = false;
  for (var i = 0; i < block.length; i++) {
   var point = block[i];
   var x = point.x;
   var y = point.y;
   if(isOverZone(x , y)){
   flag = true;
   break;
   }
  }
  return flag;
  }
  
  function drawLevelScore() {
  
  }
  /**

  * 将不能移动的各种填充至地图

  */
  function add2GameMap() {
  for (var i = 0; i < block.length; i++) {
   var point = block[i];
   var x = point.x;
   var y = point.y;
   var gameMapRow = gameMap[y]; //获取到地图的一行
   gameMapRow[x] = true; //将此行中的某个格子标记为堆积物
   gameMap[y] = gameMapRow; //再将行给设置回来
  }
  }
  function moveLeft() {
  moveTo(-1, 0);
  }
  function moveRight() {
  moveTo(1, 0);
  }
  function quickDown() {
  while (moveTo(0, 1));
  }
  function moveTo(moveX, moveY) {
  var move = canMove(moveX, moveY, block); //判定是否可以移动
  if (move == null) {
   return false;
  }
  clearBlock();
  for (var i = 0; i < block.length; i++) {
   var point = block[i];
   point.x = point.x + moveX;
   point.y = point.y + moveY;
  }
  drawBlock();
  return true;
  }
  /**

  * 下一个方块

  */
  function nextBlock() {
  blockIndex = getRandomIndex();
  block = getPointByCode(blockIndex);
  context.fillStyle = getBlockColorByIndex(blockIndex);
  drawBlock();
  }
  document.onkeypress = function(evt) {
  var key = window.event ? evt.keyCode : evt.which;
  switch (key) {
   case 119: //向上旋转 W
   round();
   break;
   case 115: //向下移动 S
   moveDown();
   break;
   case 97: //向左移动 A
   moveLeft();
   break;
   case 100: //向右移动 D
   moveRight();
   break;
   case 32: //空格键快速下落到底
   quickDown();
   break;
  }
  }
  /*设置监听移动端使用时的按钮使用*/
  var sbtn = document.getElementById("sbtn");
  sbtn.addEventListener('touchstart',function(){
    round();
  })//W
  var ybtn = document.getElementById("ybtn");
  ybtn.addEventListener('touchstart',function(){
    moveRight();
  })//D
  var xbtn = document.getElementById("xbtn");
  xbtn.addEventListener('touchstart',function(){
    moveDown();
  })//S
  var zbtn = document.getElementById("zbtn");
  zbtn.addEventListener('touchstart',function(){
    moveLeft();
  })//A
  var kgbtn = document.getElementById("kgbtn");
  kgbtn.addEventListener('touchstart',function(){
    quickDown();
  })//空格

  /**

  * 判定是否可以移动

  * @parammoveX 横向移动的个数

  * @parammoveY 纵向移动的个数

  */
  function canMove(moveX, moveY, currentBlock) {
  var flag = true;
  var newPoints = new Array();
  for (var i = 0; i < currentBlock.length; i++) {
   var point = currentBlock[i];
   var tempX = point.x + moveX;
   var tempY = point.y + moveY;
   if (isOverZone(tempX, tempY)) {
   flag = false;
   break;
   }
  }
  if (flag) {
   for (var i = 0; i < currentBlock.length; i++) {
   var point = currentBlock[i];
   var tempX = point.x + moveX;
   var tempY = point.y + moveY;
   newPoints[i] = {
    x: tempX,
    y: tempY
   };
   }
   return newPoints;
  }
  return null;
  }
  /**

  * 判定是否可以移动

  * @paramx 预移动后的横坐标

  * @paramy 预移动后的纵坐标

  */
  function isOverZone(x, y) {
  return x < minX || x >= maxX || y < minY || y >= maxY || gameMap[y][x];
  }
  document.body.click();
  
  gameTimer = window.setInterval(moveDown , 800);
  
  /**

  * 初始化方块的基础数据

  */
  function basicBlockType() {
  var arrays = new Array();
  arrays[0] = [{x: 4,y: 0}, {x: 3,y: 0}, {x: 5,y: 0}, {x: 6,y: 0}];//一
  arrays[1] = [{x: 4,y: 0}, {x: 3,y: 0}, {x: 5,y: 0}, {x: 4,y: 1}];//凸
  arrays[2] = [{x: 4,y: 0}, {x: 3,y: 0}, {x: 5,y: 0}, {x: 3,y: 1}];//L镜像
  arrays[3] = [{x: 4,y: 0}, {x: 5,y: 0}, {x: 3,y: 1}, {x: 4,y: 1}];//z
  arrays[4] = [{x: 4,y: 0}, {x: 5,y: 0}, {x: 4,y: 1}, {x: 5,y: 1}];//田
  arrays[5] = [{x: 4,y: 0}, {x: 3,y: 0}, {x: 5,y: 0}, {x: 5,y: 1}];//L
  arrays[6] = [{x: 4,y: 0}, {x: 3,y: 0}, {x: 4,y: 1}, {x: 5,y: 1}];//s
  return arrays;
  }
  function basicBlockColor() {
  return ["#A00000", "#A05000", "#A0A000", "#00A000", "#00A0A0", "#0000A0", "#A000A0"];
  }
  function getBlockColorByIndex(typeCodeIndex) {
  var arrays = basicBlockColor();
  return arrays[typeCodeIndex];
  }
  /**

  * 根据编号返回指定编号的方块

  * @paramtypeCodeIndex 方块编号索引

  */
  function getPointByCode(typeCodeIndex) {
  var arrays = basicBlockType();
  return arrays[typeCodeIndex];
  }
  /**

  * 获取随即出现方块的范围值

  * @paramlens 随机数的范围

  */
  function getRandomIndex() {
  return parseInt(Math.random() * arrays.length, 10);
  }
  /**

  * 绘制方块，按格子单个绘制

  */
  function drawBlock() {
  drawGrid();
  for (var i = 0; i < block.length; i++) {
   var point = block[i];
   var start = point.x * size;
   var end = point.y * size;
   context.fillStyle = getBlockColorByIndex(blockIndex);
   context.fillRect(start, end, size, size);
   context.strokeStyle = "black";
   context.strokeRect(start, end, size, size);
  }
  drawShadowBlock();
  }
  /**

  * 绘制障碍物

  */
  function roadBlock(x, y) {
  context.fillStyle = "darkgray";
  var start = x * size;
  var end = y * size;
  context.fillRect(start, end, size, size);
  }
  /**

  * 绘制新的方块先清除之前的方块

  */
  function clearBlock() {
  for (var i = 0; i < block.length; i++) {
   var point = block[i];
   var start = point.x * size;
   var end = point.y * size;
   context.clearRect(start, end, size, size);
  }
  }
  /**

  * 初始化一个新的行

  */
  function initGameMapRow() {
  var array = new Array();
  for (var i = 0; i < maxX; i++) {
   array[i] = false;
  }
  return array;
  }
  /**

  * 根据坐标清除指定格子的内容

  * @paramx 横坐标

  * @paramy 纵坐标

  */
  function clearBlockByPoint(x, y) {
  var start = y * size;
  var end = x * size;
  context.clearRect(start, end, size, size);
  }
  /**

  * 清掉所有位置的空白格的绘图

  */
  function clearAllNullPoint() {
  for (var i = 0; i < maxY; i++) {
   for (var j = 0; j < maxX; j++) {
   if (gameMap[i][j] == false) {
    clearBlockByPoint(i, j);
   }
   }
  }
  }
  /**

  * 绘制网格线

  * @paramcontext 绘图对象

  */
  function drawGrid() {
  clearAllNullPoint(); //清除掉当前方块下落位置造成的阴影
  context.strokeStyle = "grey"; //画笔颜色
  for (var i = 0; i <= maxX; i++) {
   var start = i * size;
   var end = start + size;
   context.beginPath();
   context.moveTo(start, 0);
   context.lineTo(size * i, size * maxY);
   context.stroke();
   context.closePath();
  }
  //绘制水平线条
  for (var i = 0; i <= maxY; i++) {
   var start = i * size;
   var end = start + size;
   context.beginPath();
   context.moveTo(0, size * i);
   context.lineTo(size * maxX, size * i);
   context.stroke();
   context.closePath();
  }
   /* 点击再来一局 */
   var again = document.getElementById("again");
   setTimeout(function() { 
     again.addEventListener('click',function(){
         
       /* 简单粗暴直接刷新 */
       location.reload(true);
   }),1000})//防止响应延迟
  }
  
        